Caution Water Blog

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Tue 20

APR 2010

A Tale of Two Rudders

I mentioned in an earlier post that the rudder for our Merlin Rocket was too long, or our lake too shallow, one of the two. The length of the rudder is the easier of the two to fix without expensive dredging equipment that the council wouldn't appreciate, so thats the direction I headed in.

The original rudder, shown below on the top, is just over 3 and a half feet long. After discussions with a friend of ours, Mike, and after scouring Ebay for second hand rudders, I decided the easiest method to solve this problem was to make a new rudder. The fancy rope/elastic/pulley downhaul system I rigged up ultimately didn't work, and on a bit of a gusty day resulted in the first unintended capsize we've had together on our lake, partly due to lack of steering, and partly due to I'm not quite sure (I dumped the mainsheet, it didn't nothing, and we still capsized).

Photo 1. New and old rudder

So, using the current blade head and our Laser 2 blade, I designed a new rudder blade template on hardboard. Two actually, one just longer than the other, both around three feet long. We have no problem with our Laser 2 rudder other than initially launching where it's about 9 inches deep, and no rudder drops down completely. I eagerly awaited our friend to price up some marine ply, which didn't happen due to him being too busy.

Instead, he did one better. He happened to drive past me one evening, called me over to the car, pointed out two rudder blades in his back seat, and asked me which one I wanted. One was a quite oddly shaped GRP one, and one looked very familiar in shape. I took it home, and checked it out. Sure enough, it was almost identical to the Merlin blade. Mike - I'll say it in writing, you're an absolute star. It's shown above in it's sanded down form, after paint removal.

It needed a few modifications. It needed a good clean and sand down first, and after two hours with a hot air paint stripper it was more or less clear of paint. It then required a sand down on the faces, and the two edges cleaning up, and the bottom edge cleaning. There was a sizeable chip taken out of the front edge at the bottom, but a bit of sandpaper treatment later you can't really tell. It's not perfect, but not bad. Quite a bit of filling then followed, to fill various dings and hollows, as shown below. More sanding followed this.

Photo 2. Rudder covered in filler

Next I needed to cut a U-shaped notch at the top - the Merlin rudder stock has a spring loaded cam in which when the blade is fully down it locks into position, instead of using a downhaul. This is great, unless you can't push the blade all the way down if you're stopped by something like, I don't know, the bottom of the lake. Rather than modify the stock by taking out the cam, it was better to modify the blade. Measured, scribed with pencil, then a series of small holes were drilled (shown in Photo 3), cut out with a hack saw, cleaned up with files, rasps and sandpaper was used to create the notch. Rudder inserted into stock in the up position (about 4mm too thin for the stock, but that's ok), and the blade unfortunately wouldn't go down. It turns out the shape of the head was a bit different after all.

Photo 3. U Shaped notch drilled

Measure. Sand. Measure. Sand. Measure. Sand. About an hour later, with about 3/8 of an inch to 1/8 of an inch removed around the head of the blade, it now all worked, fitted in the stock properly, and rotated into position, with the cam locked in place. Unfortunately, it locked in place a little too well, as the angle of the notch was a bit too extreme for it to come out again. More measuring and sanding, and eventually I got to the point where it locks into position, but a relatively light knock on the front of the blade will kick it back up, rather than stick it in the mud at the bottom of the lake, but the water pressure shouldn't be strong enough to knock it out of place. I pretty much gave up taking photos at this point as the camera was getting a bit dusty with all the sanding.

So, it's now ready for finishing. Rather than marine ply, it seems to be some sort of hardwood (god knows it blunted enough sandpaper), so I don't need to worry too much about it swelling on the approximately 2 hours of contact it may have a week with water. After discussing my options, varnish was eliminated as taking too much time, too many coats, not being hardwearing enough, and the wood finish was still partly covered in paint so it would have looked rubbish.

Gelcote was then eliminated as the gelcote I have which I thought would work is missing a waxing agent, and would take far too long anyway.

Ultimately, I've gone with a multicoat marine paint, which cost me £15. I looked at separate primers and white topcote and didn't want to spend in excess of £30 on enough paint to cover half a hull just for one rudder blade. So far it's had a brush applied base coat, and will shortly receive a gloss roller applied topcoat. I don't think that will be enough - but it's enough to seal it for a test run this weekend. When the paint is dry, two ropes need to be applied (no more nails plus a few nails, ironic eh) as an uphaul and downhaul, and if it needs more coats of paint it will get them. More photos on that later.

Did I mention after sailing now for an hour in the Merlin, I plan to do our clubs 5 hr race for the RNLI in it, in only 2 and a half weeks time? Unless it's too windy, in which case we'll jump into the Laser 2. Becky has, naturally, abandoned me and plans to sail on her own in her Laser 1 for 5 hours. I don't think I stand much chance of beating her, but I'm sure I'll pay for it if I do get lucky.

PS Sorry for the lack of updates lately. A Laser 2 rigging guide will be with you shortly.